Set let require_unimplemented_servers default to true when generating code from .proto files (#37737)

* Remove `require_unimplemented_servers=false` option when generating code from proto files. Run `make protobuf`.

This allows require_unimplemented_servers to default to true, and the generated code shows the impacts of that.

* Update generator script to embed 'UnimplementedFoobarServer' structs and skip generating code for the `mustEmbedUnimplementedFoobarServer` method that is implemented via that embedding.

* Run `make generate`

* Embed UnimplementedProviderServer into implementations of ProviderServer

* Embed UnimplementedProvisionerServer into implementations of ProvisionerServer

Author: SarahFrench

internal/cloudplugin/cloudproto1/cloudproto1_grpc.pb.go

@@ -34,6 +34,8 @@ type provider struct {
 	provider        providers.Interface
 	schema          providers.GetProviderSchemaResponse
 	identitySchemas providers.GetResourceIdentitySchemasResponse
+
+	tfplugin5.UnimplementedProviderServer
 }
 
 func (p *provider) GetMetadata(_ context.Context, req *tfplugin5.GetMetadata_Request) (*tfplugin5.GetMetadata_Response, error) {

internal/grpcwrap/provider.go

@@ -35,6 +35,8 @@ type provider6 struct {
 	provider        providers.Interface
 	schema          providers.GetProviderSchemaResponse
 	identitySchemas providers.GetResourceIdentitySchemasResponse
+
+	tfplugin6.UnimplementedProviderServer
 }
 
 func (p *provider6) GetMetadata(_ context.Context, req *tfplugin6.GetMetadata_Request) (*tfplugin6.GetMetadata_Response, error) {

internal/grpcwrap/provider6.go

@@ -29,6 +29,8 @@ func Provisioner(p provisioners.Interface) tfplugin5.ProvisionerServer {
 type provisioner struct {
 	provisioner provisioners.Interface
 	schema      *configschema.Block
+
+	tfplugin5.UnimplementedProvisionerServer
 }
 
 func (p *provisioner) GetSchema(_ context.Context, req *tfplugin5.GetProvisionerSchema_Request) (*tfplugin5.GetProvisionerSchema_Response, error) {

internal/grpcwrap/provisioner.go

@@ -125,6 +125,11 @@ func main() {
 			fmt.Fprintf(&buf, "type %s struct {\n", baseName)
 			fmt.Fprintf(&buf, "impl %s.%s\n", shortName, ifaceName)
 			fmt.Fprintln(&buf, "mu sync.RWMutex")
+
+			unimplementedServerInterface := fmt.Sprintf("%s.Unimplemented%s", shortName, ifaceName) // UnimplementedFoobarServer struct name that's generated from the proto file.
+			unimplementedServerMethod := fmt.Sprintf("mustEmbedUnimplemented%s", ifaceName)         // Name of the method implemented on UnimplementedFoobarServer.
+			fmt.Fprintln(&buf, unimplementedServerInterface)                                        // Embed UnimplementedFoobarServer struct into the struct we're generating.
+
 			buf.WriteString("}\n\n")
 
 			fmt.Fprintf(&buf, "var _ %s.%s = (*%s)(nil)\n\n", shortName, ifaceName, baseName)
@@ -135,6 +140,13 @@ func main() {
 
 			for i := 0; i < iface.NumMethods(); i++ {
 				method := iface.Method(i)
+
+				if method.Name() == unimplementedServerMethod {
+					// Code for this method doesn't need to be generated.
+					// The method is present via embedding, see use of `unimplementedServerInterface` above.
+					continue
+				}
+
 				sig := method.Type().(*types.Signature)
 
 				fmt.Fprintf(&buf, "func (s *%s) %s(", baseName, method.Name())